VolgaCTF Quals 2014 - Reverse 200

Reverse Code Engineering — 200

You just need to put 2 numbers in ascending order without spaces.
btsync: BNBPTYNHZR2FGRLULM5G3XHT4T6XDZK4E
direct link

 You can read my write-up at the Hardc0de team blog.

[Reverse] Simple code deoptimization

In this post I would like to write about code deoptimization strategies and where it may be needed.

First of all there is quite a little use of deoptimization and that is why I haven't found anything about it in the Internet. Usually developer should write the fastest running code that is possible. Therefore if he/she writes very inefficient code that will cause program to delay on simple functions and that developer will be fired or noone will accept such performance.

CSCAMP CTF Quals 2013 - Reverse 150 write-up

In this task we are given a x86-64 binary that prints a string.

CSCAMP CTF Quals 2013 - Reverse 100 write-up

Unfortunately tasks currently are unavailable, so I cannot copy task and its name.

We are given a .NET application (You can verify this using file utility.) which checks password. You can try to guess it, but this won't help you anyhow.

Crackmes [Reverse write-up] - Trojaner's Patch/InjectMe write-up (DLL injection)

Task from crackmes:

Patch or Inject it with a DLL, so that it will show the goodboy message :)
Happy Hacking!

Hacklu CTF 2013 - Reverse 150 - RoboAuth

Task:

Oh boy, those crazy robots can't catch a break! Now they're even stealing our liquid gold from one of our beer tents! And on top of that they lock it behind some authentication system. Quick! Access it before they consume all of our precious beverage!

Download: https://ctf.fluxfingers.net/static/downloads/roboauth/RoboAuth.exe

Flag: password1_password2

Sharif CTF Quals 2013 - Reverse 300 - HelpMe

Task:

Download

We are provided with a Java archive (jar) that can be used to encrypt a file using an AES block cipher.

Sharif CTF Quals 2013 - Reverse 200 - Reverse200

Task:

Download

We are provided with an x86 ELF executable that crashes while trying to decrypt a key.

Sharif CTF Quals 2013 - Reverse 100 - Vault

Task:

Download

In this task we have to open a huge lock. We are provided with .NET binary and the task is the same as usual: get a flag!

Crackmes [Reverse] - TRVCrackme v1.0 (MIPS) [Very easy level]

In this task we are given a binary compiled for MIPS architecture. Therefore to execute it you have to find workstation that have MIPS architecture or emulate its behavior. Of course you can produce keygen without even executing it, because the logic is quite straighforward. By the time I managed to execute it I have already understood what it does.

CSAW CTF Quals 2013 - Reverse 500 - Impossible

Task:

Impossible - 500 Points

Solved by 82 teams.

WTF, his hp is over 9000! Beat the game to get your key.
impossible.nds

In this task we are provided with an image of the Nintendo DS cartridge with a game. The task clearly says we have to win probably cheating. Firstly I installed IDA loader for .nds files (You can find it in the net) but this haven't helped me a lot: there were a lot of ARM code and no clues how to get to the flag.

CSAW CTF Quals 2013 - Reverse 400 - keygenme

Task:

keygenme - 400 Points

Solved by 100 teams.

nc 128.238.66.219 14549
keygenme32.elf

We are given a x86 ELF executable. It takes 3 arguments(username, token1, token2) and prints whether they are good(*<:-)) or not. ( :-( ). In this task we need to write a keygen that will communicate with judges server, which sends username to keygen, and then send them valid token pair for each username.

Crackmes [Reverse] - kaliba CrackMe [very easy level]

In this task we are provided with a binary that asks for a serial code.

After you provide some arbitrary serial number, application rejects it. You may be quite lucky to guess it.

Crackmes [Reverse] - second keygenme [Very Easy level]

In this task we are provided with a windows binary. We have to understand how it works and provide a valid registration name/serial number pair or write a keygen. This program simply asks for those two strings(name/serial) and if the serial code is wrong, it terminates.

ASIS CTF 2013 - Reverse 200 - Masterpiece

Task:

file